The sequencing of the human genome was in part accomplished through engineering achievements in polymer science, and followed a paradigm shift in electrophoresis technology from slab gels to capillary electrophoresis. This shift is continuing with a movement towards microfluidic chips, and for these miniaturized platforms, there is a need for high-performance biomolecule separation media that can be loaded into microdevices with ever-decreasing footprints. For high-performance genetic analysis on chips, a fresh “gel” is required for each analysis. Covalently crosslinked polyacrylamide gels, once the gold standard for electrophoretic DNA separations, are monolithic and cannot be loaded and reloaded into microchannels, while in vitro polymerization of acrylamide in confined microchannels yields poor separation media.
To address this problem, various “replaceable” linear polymer and copolymer solutions have been developed as DNA separation media for capillary and microchip electrophoresis systems. Among the more notable approaches taken to improve microchannel DNA separations using pre-formed polymers are the use of entangled solutions of high-molar mass linear polymers (particularly polyacrylamide and polydimethylacrylamide), as well as novel polymers with diverse non-linear architectures and properties (e.g., thermo-responsive linear copolymer networks, branched copolymers, and sparsely crosslinked nanogel solutions). While results have been encouraging, the search continues in the art for new polymeric compounds and improved separation.